The term "dioxins" is used to describe a group of toxic persistent organic chemicals that remain in the environment for a long time. These compounds can accumulate in the body fat of animals and humans and have a tendency to remain unchanged for prolonged intervals, giving rise to concern for adverse effects in humans.
The Department of the Environment and Heritage published the first Australian inventory of dioxin emissions to air in 1998 (Sources of Dioxins and Furans in Australia: Air Emissions). As there were few Australian data on dioxins, the preparation of this inventory relied heavily on overseas data, using estimation methodology. The limited monitoring data available indicated that environmental concentrations are generally low, but there is insufficient information to assess the impact of dioxins in Australia.
At its meeting in December 2000, the Australian and New Zealand Environment and Conservation Council (ANZECC ) requested the development of a discussion paper for use in consultation with stakeholders. In April 2001, public meetings were held in several cities across Australia to seek public input into the development of a possible national dioxins program. Following on from these consultations, a proposal for a national dioxins program was tabled at the meeting of ANZECC in June 2001. At this meeting, Council noted that the Australian Government would fund a National Dioxins Program (NDP) with $5 million over four years and that this program would generate data over the following two years which can be used to determine whether a regulatory approach would be required to manage dioxins.
This document sets out the priorities for the program. It will be revised and updated during the program as work progresses.
|What are Dioxins?
"Dioxins" refers to the polychlorinated dibenzodioxins (PCDDs), a group of persistent chlorinated chemical compounds, which have certain similar chemical structures and properties, and have similar biological characteristics including toxicity. Sometimes the term "dioxin" is also used to refer to the most well studied and most toxic PCDD, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD).
For the purposes of the National Dioxins Program, "dioxins" is used in the broader sense and is also taken to include the closely related polychlorinated dibenzofurans (PCDFs or furans) and co-planar polychlorinated biphenyls (PCBs) (co-planar PCBs are those PCBs that can assume a flat configuration, making them structurally similar to PCDDs and PCDFs). Several hundred of these closely related PCDD, PCDF and PCB compounds exist, of which 29 are considered to have significant toxicity and are the main focus of the NDP.
Dioxins serve no useful purpose and are not intentionally produced, but rather are unintended by-products released in small quantities from some human activities (combustion processes of any type, including power generation, metal works and waste incineration, as well as certain types of chemical manufacture) and some natural activities such as bushfires and volcanic activity. They occur in trace amounts as contaminants in air, water and soil throughout the world.
The 2001-02 Federal Budget provided $5 million for the program over four years from July 2001 to June 2005.
The NDP objectives are to:
The key actions of the NDP will be implemented over three phases as shown in Figure 1:
Phase One - gather as much data as possible about levels of dioxins in Australia;
Phase Two - assess the impact of dioxins on human health and the environment; and
Phase Three - in light of these assessed impacts, to reduce and where feasible, eliminate releases of dioxins in Australia.
If Australia ratifies the Stockholm Convention on Persistent Organic Pollutants, the NDP will contribute to meeting our obligations in relation to dioxins even though the program has arisen from domestic concerns and will proceed to recommendations and actions independent of the Convention.
Dioxins are predominantly generated as unintended by-products of combustion processes and are, thus, most usually discharged into the air. Air, therefore, represents the primary route of deposition of dioxins to the environment. It has been estimated that 96% of dioxins present in the environment have arisen from air emissions. They can then be deposited on plant, soil and water surfaces. Dioxins can then enter the food chain when animals eat contaminated leaves. In aquatic environments, filter-feeding animals can absorb dioxins when they filter sediments or particulate matter floating in the water. The dioxins are then absorbed into the animal fat. Dioxins increase in concentration as they migrate up the food chain. The consumption of animal products with high fat content, such as meat and dairy goods, can increase human exposure to dioxins.
Given these factors, the main priorities for the NDP will be to carry out studies to determine the levels of dioxins in humans and the environment and to assess the relative importance of sources of dioxin emissions. Results of studies on dioxins by other Australian Government programs or agencies will also improve our knowledge on dioxin levels in Australia.
The data gathering and consolidation phase of the program will run from mid 2002 through to late 2003 and aims to:
Up to $2.5 million has been allocated for Phase One with much of the work to be carried out through contracts let by the Australian Government to well respected scientific organisations.
Dioxins accumulate in body fat and the average concentration increases progressively with age. The measurement of dioxins in humans is an important indicator of dioxin exposure and is extremely useful in determining trends. Trend analysis is an important tool in determining the effectiveness of measures taken to reduce dioxins. To determine the levels of dioxins in the Australian population, two studies will be undertaken by assessing the levels of dioxins in human breast milk and in blood serum.
This study aims to assess the level of dioxins in the body by using the amount found in pooled breast milk samples as an indicator of total body levels. Dioxins accumulate in the food chain, particularly in fat containing foods and when humans consume foods, the dioxins in the food remain in the body's fat stores. Since breast milk is a rich source of fat, analysis of the levels of dioxins in breast milk is valuable for estimating the total amount of dioxins in humans.
In this study, breast milk samples will be taken from 200 first time mothers from metropolitan and rural areas in Australia.
The blood serum study will analyse pooled blood samples collected from up to 10,000 male and female donors in four metropolitan and one rural area across Australia in five age groups; <15, 15-30, 30-45, 45-60 and >60 years.
International studies have concluded that around 95% of human exposure to dioxins (and other chlorinated chemical compounds) is through food, particularly those foods containing animal fats such as meat and dairy products. Dietary exposure to dioxins can be estimated by determining the concentrations of dioxins in foods likely to contain dioxins and then multiplying these results by the consumption of these foods. This involves sampling of representative foods from the marketplace and analysing these for dioxins content.
Food Standards Australia New Zealand (funded by the Department of Health and Ageing) will analyse the levels of dioxins in a variety of meat, fish, eggs and dairy foods taken from retail outlets during 2000 in all State and Territory capitals. The samples are generally those foods that are consumed in significant amounts in the Australian diet and have been prepared to a 'table-ready' state (e.g. cooked) and, thus, best represent the amounts of dioxins that would be consumed.
The National Residue Survey (administered by the Department of Agriculture, Fisheries & Forestry - Australia) is analysing dioxins levels in approximately 240 samples of agricultural commodities such as meat and dairy products collected across Australia. The number of samples for each type of product is based on the proportion of the total production of that commodity. The findings will be reported as national data and will not identify individual properties.
Studies will be carried out to determine the ambient level of dioxins in a range of environmental media including air, aquatic environments, soils and fauna. Where possible, these studies will take samples from three broad areas: metropolitan, agricultural and remote areas such as national parks and other Crown lands.
The objective of this project is to characterise dioxin levels in ambient air in Australia. This will be achieved by sampling air on a monthly basis over a twelve month period at locations in metropolitan, agricultural and remote areas. These measurements will characterise seasonally dependent factors including bushfire smoke and residential wood-heater smoke in areas where these sources impact strongly on air quality.
The objective of this project is to characterise dioxin levels in Australian soils. Sampling will be carried out in a range of climates and landforms across Australia and where possible in areas close to the air sampling sites. Several samples will be collected from each area and combined to form one aggregate sample for the analysis.
Overseas studies have found that detecting the presence of dioxins in water is unlikely, as dioxins are insoluble in water. It is, therefore, more cost effective to concentrate on sampling from sediments and biota where the dioxins are more likely to accumulate.
This study will involve the analysis of dioxins in a range of representative fauna and sediment samples obtained from freshwater, estuarine and marine environments. The fauna will include common species of fish and sedentary species that are known to accumulate toxic substances, e.g. oysters and mussels. Where possible the sediment samples will be collected in the same area as the fauna. Areas that are subject to dredging or similar periodic disturbance will be avoided.
The objective of this project is to characterise the levels of dioxins in range of terrestrial fauna. The species to be covered by the project could include macropods, birds, such as birds of prey, lizards and soil invertebrates. Where possible the samples will be taken from animals that have been killed accidentally by motor vehicles and from the same areas where the soil and air sampling will be undertaken.
The 1998 inventory identified a range of sources of dioxins emissions to air of which six may contribute up to 95% of the total amount - bushfires (both wild fires and prescribed burning), residential wood combustion, coal combustion, sinter production and industrial wood combustion. However, as these estimates were based largely on overseas studies, the following projects will attempt to provide more accurate data.
The 1998 inventory estimated that bushfires may contribute up to 75% of the total dioxins in Australian environment. The objective of this project is to characterise dioxin emissions from bushfires in Australia. This will be achieved by sampling smoke from either wildfires or prescribed burns, and in laboratory controlled fires. A variety of vegetation categories will be examined including native forests and woodlands, pine plantations and agricultural crop residues.
Overseas studies show that motor vehicles may contribute less than 3% of the total dioxins emissions in a country. Nevertheless, a study will be undertaken to determine the probable contribution to the dioxin emissions from this source. The study will involve examining studies of motor vehicle emissions in other countries and comparing these with the Australian motor vehicle fleet. Factors such as the composition of the Australian fleet, types of fuels used and their additives, emission control standards and driving patterns, including distances travelled, will be taken into consideration when extrapolating the overseas data to Australia.
Under the "Living Cities - Air Toxics Program", the Department of the Environment and Heritage published in March 2002 the technical report: Emissions from Domestic Solid Fuel Burning Appliances. This report, includes measurements of dioxins emissions from domestic wood heaters.
Many Australian industrial facilities monitor emissions of substances as part of regulatory requirements or as a commitment to ensuring their processes are operating efficiently and with minimal environmental effects.
Data on estimations of dioxin emissions from industrial and other sources will be provided as part of the reporting requirements under the National Pollutant Inventory (NPI). Estimations of dioxins emissions were reported for the first time in the fourth reporting year of the NPI, i.e. 1 July 2001 - 30 June 2002. Data for this period was made publicly available in January 2003. For the most part NPI dioxins emissions data are estimations and not actual monitoring data, therefore, care will be needed in interpreting them.
|Limitations of the Phase One studies
Because dioxins are toxic at very low levels, their presence in substances is measured in parts per trillion. Analysis, therefore, requires highly sensitive equipment and is time consuming and costly - the costs for the analysis alone may be up to $2,000 per sample. This is in addition to any costs associated with collection of the samples.
Accordingly, the number of samples that will be analysed for the studies are low e.g. for the environmental study there will be around 400 samples across the four components. Despite the low numbers of samples, the results will still provide a valuable picture of the indicative levels of dioxins in Australia
The data gathered through the studies funded under the NDP, other government programs, data collected by non-government groups, NPI reporting and excisting data, will be used to prepare a new inventory of dioxins in Australia. It is expected that work on the inventory would commence in mid 2003 and continue through to late 2003 as the results of the Phase One studies become available.
Phase Two will use the findings of Phase One as a basis to assess the potential risks of dioxins to the environment. An assessment will also be made of the potential risks for human health from exposure to dioxins either directly from the environment or from dioxin contaminated food. The risk assessment will also take into consideration research done in other countries.
The Office of Chemical Safety within the Department of Health and Ageing will undertake the human health assessment while the environmental risk assessment will be undertaken by the Department of the Environment and Heritage. It is understood that Australia would be the first country in the world to attempt an environmental risk assessment of dioxins, other assessments have focussed only on the impacts to human health.
The risk assessment phase will begin in mid 2003 and be completed by early 2004.
The outcome of the risk assessment phase will be used to inform the policy development phase. This will include developing national management measures to reduce, and where feasible, eliminate dioxins in Australia. In this phase, an assessment will be made of the excisting regulatory framework (applied in each jurisdiction) and the consequence of no action. An assessment will also be made of what regulatory forms are suitable from guidelines through to mandatory standards.
Subject to the outcomes of the risk assessment, management measures could include:
The combination of measures that might ultimately be implemented will be a matter for State and Territory governments. In considering management measures, governments will need to give due consideration to cost benefit analysis and the Precautionary Principle.
Phase Three would begin late 2004.
The following dates are for planning purposes and may be subject to change.
|Phase One - data gathering projects commence||July 2002|
|Phase One - data gathering projects - progress reports received||November 2002|
|Phase One - data gathering projects - final reports received||Late 2003|
|Phase One - Inventory compilation commences||Mid 2003|
|Phase One - Inventory completed||Late 2003|
|Phase Two - impact assessment commences||Mid 2003|
|Phase Two - impact assessment completed||Early 2004|
|Report to EPHC on outcomes of Phases One and Two||October 2004|
|Phase Three - development measures commence||Late 2004|
|National Dioxins Program ceases||June 2005|
A review of progress will be undertaken near the end of each phase to ensure the program is on track in terms of meeting the target dates.
Two bodies, the National Dioxins Project Team (NDPT) and the National Dioxins Consultative Group (NDCG), established to advise on the direction of the program will play a key role in communicating with stakeholders as shown in Figure 2.
The NDPT, chaired by the Department of the Environment and Heritage, comprises representatives of State and Territory environment protection agencies and representatives of the Primary Industries Ministerial Council (PIMC) and the Australian Health Ministers' Conference (AHMC). Under the direction of the Australian Government, the role of the NDPT is to:
The NDCG, chaired by the Department of the Environment and Heritage, comprises representatives from industry, scientific research and community interest organisations. Under the direction of the Australian Government, the role of the NDCG is to:
In addition to consulting through these bodies, opportunities will be provided to seek broader community views during the risk assessment.
A further public consultation process will also be undertaken during the development of measures.
For further information on the National Dioxins Program:
National Dioxins Program
c/- Chemical Policy Section
Department of the Environment, Water, Heritage and the Arts
GPO Box 787
CANBERRA ACT 2601